This invention concerns compositions employing known growth regulating agents. The compositions have improved properties over the respective ingredients, particularly in the regulation of seedhead formation in grasses.
The plant growth regulation art has now advanced to a stage in which compounds are available which can cause very specific and selective affects upon the growth and development of certain plants. For example, several agents are now in commercial use which either kill or greatly retard the growth of one or several grassy or broadleaf weeds, yet exhibit little or no adverse affect upon the growth and development of desired crop plants such as soybeans, cotton, corn and the like. The discovery and development of compounds which exhibit such selective herbicidal activity has virtually revolutionized the agriculture industry.
Since a great deal of efficacious selectivity often is associated with compounds which are useful due to their plant growth regulant activity, it is difficult or impossible to achieve a broad range of responses utilizing a single plant growth regulating agent. Consequently, the use of combinations of one or more selective agents sometimes is required in order to achieve a desired plant response.
The selectivity and limitations of growth regulator activity displayed by certain agents which affect the growth of various turfgrass species has severely limited the widespread commercial use of such agents. For example, mefluidide, a compound disclosed in U.S. Pat. No. 3,894,078, is a plant growth regulator which is effective in suppressing the seedhead formation in various turfgrass species. Mefluidide also causes a cessation of vegetative growth for a relatively short period of time when applied at adequate rates. In contrast, .alpha.-(1-methylethyl)-.alpha.-[4-trifluoromethoxyphenyl]-5-pyrimidinemet hanol, a compound described in U.S. Pat. No. 4,002,628, is very effective in regulating the growth of various turfgrass species, but limited retardation of seedhead formation is manifested. As a result, the use of such growth regulator is restricted since turf having an abundance of seedheads is unsightly, even though the overall turf remains at a desirably short height.
With this invention, it has been discovered that a novel composition comprised of mefluidide and .alpha.-(1-methylethyl)-.alpha.-[4-trifluoromethoxyphenyl]-5-pyrimidinemet hanol overcomes the many disadvantages associated with the use alone of the respective compounds. An object of the invention accordingly is to provide novel plant growth regulator compositions which are particularly useful as plant growth regulators for various turfgrasses. Additionally, the invention provides a method for regulating the growth of plants employing the novel compositions. The compositions of this invention provide a more immediate effect and a more prolonged growth retardation than is encountered with the use of either active ingredient alone. The compositions are particularly useful for the inhibition of seedhead formation in turfgrasses, including pasture grasses upon which domestic animals graze.